Wiring ducts



May 28, 1963 J. K. STUESSEL WIRING DUCTS Filed NOV. 14, 1962 INVENTOR. JO/J/V K. STUESSEL J and:

United States Patent 3,091,657 WIRING DUCTS John K. Stuessel, Dayton, Ohio, assignor to Flexifior Electrical Systems, Inc., Dayton, Ohio, a corporation of Ohio Filed Nov. 14, 1962, Ser. No. 237,499 2 Claims. (Cl. 174-63) This invention relates to wiring ducts and more particularly to wiring ducts for support from ceilings, rafters or even walls.

A duct embodying the present invention is illustrated in connection with a ceiling formed by precast hollow slabs such as is described in United States Patent No. 2,299,111. Such slabs are used as structural elements and are frequently disposed in side by side relation to provide a ceiling structure for one room and a floor or sub-floor for a room above. Slabs of this character have longitudinal passages therethrough to conserve concrete and at the same time improve the stress characteristics of the slab. These longitudinal passages are frequently utilized as raceways for electric wiring and cables. It is desirable in many instances to draw the wiring from a slab raceway transversely of the slab to the ceiling below and then conduct such wiring transversely of the slabs in steel duct for distribution purposes.

Steel ducts of the character referred to above will frequently carry a large number of wires for distances of the order from ten to several hundred feet, depending upon the size of the building involved. Such steel duct when attached or supported from rafters or ceiling has a bottom cover for closing the duct. In conventional ducts, it is necessary to provide means for supporting the wiring in the duct to prevent the same from falling if and when the cover is removed. If no support means are provided, it is necessary to prevent the wiring from falling outside of the duct when the cover is applied.

This invention provides a simple and effective duct construction wherein a simple means is provided for reinforcing the duct and providing a support for the duct cover and at the same time providing a support for wiring within the duct. An embodiment of the invention is illustrated in the drawing wherein:

FIGURE 1 is a view partly in section showing a length of duct embodying the present invention, with the end broken away and the duct cover in position, the entire duct being shown below a ceiling.

FIGURE 2 is an enlarged detail of a portion of the duct illustrated in 'FIGURE 1, with the wire holder and reinforcing means shown in enlarged view.

FIGURE 3 is a View of a detail of the duct illustrating the manner in which the :duct cover is locked in position.

As illustrated here, a plurality of slabs of the precast concrete type are shown in side-by-side relation to form ceiling 10. These slabs may be simple precast slabs such as is illustrated in the patent referred to above or may be of the type having steel reinforcement with or without prestressing for obtaining desirable loading characteristics. Since the slabs form no part of the present invention, no further description thereof is deemed necessary except that slabs are provided with longitudinal passages 12, at least one of which is illustrated here as accommodating wiring 13.

As illustrated here, it is necessary to pull down Wiring 13 transversely of a slab and for this purpose the concrete wall is broken through and grommet 1-5 is rigidly attached to the duct to provide access to passage 12 for the wiring. The particular details of grommet 15 are not important. Grommet 15 may be of steel or similar material and is rigidly attached to the duct body. As an example, the grommet construction disclosed and ice claimed in the copending application of Stuessel and Segerlund, Serial No. 228,197, filed October 3, 1962, and assigned to the same assignee, may be used. Instead of a grommet, any other means for introducing the wiring into a duct may be utilized, so long as the conductors are protected from the raw cut concrete edges and steel duct edges. As illustrated here, steel duct 20 may be suitably attached by nails or bolts in conventional fashion. The duct is illustrated in a normal inverted position. Duct 20 is of steel and consists of flat bottom 21, depending sides 22 and 23 and in turned cover edge portions 24 and :25 respectively. The duct may be formed in any desired lengths, usually eight, ten or twelve feet, and may have any desired width such as five, six or eight inches, as examples. The depth of the duct may be, for example, about two or three inches. The duct is made of galvanized sheet steel of any suitable gauge, such as No. 14, having a thickness of about .072 inch.

Cover edge portions 24 and 25 of the duct are marginal portions which extend toward each other and may be about -%s or /2" in width, depending upon requirements. Cooperating with duct body 20 is duct cover 27 having sides 28 and 29 dimensioned to fit over sides 22 and 23 of the duct body. The gauge of metal used for cover 27 may be the same as the duct body or lighter. Sides 28 and 29 of the duct cover extend laterally from cover 27 for a short distance of the order of about /8" or /2".

To reinforce sides 22 and 23 of the duct body, spring bows 35 are provided at spaced intervals along the duct. As an example, spring bows 35 may be disposed at two or three-foot intervals so that a length of duct cover will have at least two of the bows for cooperation therewith. Since the bows are all alike, only one need be described in detail. Bow 35 is of spring steel or any other metal providing the flexibility and is sufliciently strong and stiff so that it will tend to impart some stiffening to the sides of duct body 20. Thus bow 35 has straight side portions 36 and 37 which extend along the inside surface of each of side walls 22 and 23 of the duct body and contacts the same for the length of the straight portion. For example, straight portions 36 and 37 may extend for about or 1 and then at the end thereof, the metal is bent sharply upwardly to form locking fingers 38 and 39 respectively.

Locking fingers 38- and 39 pass through suitable apertures in side walls 22 and 23 of the duct body. These apertures are disposed near the edges of the side walls adjacent the inwardly directed cover edge portions 24 and 25. The length of locking fingers 38 and 39 are such that each one will be equal to the combined thicknesses of the metal forming the cover sides 28 and 29 and side walls 22 and 23 of the duct body. In order to apply duct cover 27, it is necessary to spring how 35 inwardly and place the cover in position, so that fingers 38 and 39 will fit into apertures in sides 28 and 29 of the duct cover. It is understood that each bow 35 has spring action and can be sprung into position as illustrated in FIGURES l and 2, prior to the application of the cover and either before or after installation of the duct.

It is understood that wiring within duct body 2d will be disposed above each of bows 35 and be supported thereby. By having a number of bows for each length of cover, a length of cover may be removed without dropping any wires to interfere with the subsequent replacement of the cover. However, the number of bows for each length of cover may be set to suit requirements. It is not necessary that the length of the cover be equal to the length of the duct body and in practice, each length of duct body may be much longer than a length of cover.

In the event that access to the interior of a duct body is required, it is only necessary to push the ends of bow 35 in and remove a length of cover from the duct body to expose the wiring, It is clear that each bow 35 will not only reinforce side walls of the duct body, but will also provide a locking pin -for the duct cover and at the same time will provide a support for the wiring.

What is claimed is:

1. A metal duct construction comprising an elongated duct body having a duct bottom and duct sides, a cover for said duct body comprising a flat portion and narrow cover side walls for overlapping the side walls of said duct body, and spring bows disposed in said duct body, each spring bow extending transversely across the duct and having locking finger portions bent outwardly and passing 15 1217398 through apertures in the side walls of the duct body, said duct cover having registering apertures in the cover sides for accommodating the fingers, whereby said cover may be locked in position and said bows may function 4 as a support for wiring when said duct body is suspended upside down with the bottom of the duct above the cover.

2. The construction according to claim 1 wherein each bow includes a straight portion adjacent the finger portion, said straight portions extending along the side Walls of the duct body within the duct body for engaging said duct body sides whereby said spring bow provides support for said sides of said duct body to maintain them 10 against distortion inwardly toward each other.

References Cited in the file of this patent UNITED STATES PATENTS Bonnell Feb. 27, 1917 2,445,198 Wiesmann July 13, 1948 FOREIGN PATENTS 660,919 Great Britain Nov. 14, 1951 

1. A METAL DUCT CONSTRUCTION COMPRISING AN ELONGATED DUCT BODY HAVING A DUCT BOTTOM AND DUCT SIDES, A COVER FOR SAID DUCT BODY COMPRISING A FLAT PORTION AND NARROW COVER SIDE WALLS FOR OVERLAPPING THE SIDE WALLS OF SAID DUCT BODY, AND SPRING BOWS DISPOSED IN SAID DUCT BODY, EACH SPRING BOW EXTENDING TRANSVERSELY ACROSS THE DUCT AND HAVING LOCKING FINGER PORTIONS BENT OUTWARDLY AND PASSING THROUGH APERTURES IN THE SIDE WALLS OF THE DUCT BODY, SAID DUCT COVER HAVING REGISTERING APERTURES IN THE COVER SIDES FOR ACCOMMODATING THE FINGERS, WHEREBY SAID COVER MAY BE LOCKED IN POSITION AND SAID BOWS MAY FUNCTION AS A SUPPORT FOR WIRING WHEN SAID DUCT BODY IS SUSPENDED UPSIDE DOWN WITH THE BOTTOM OF THE DUCT ABOVE THE COVER. 